Safety and locking device for a disconnecting switch



Sept. 9, 1947. '.1, w, GRONBECK 2,427,134

SAFETY AND LOCKING DEVICE FOR A DISCONNECTING SWITCH I I Filed March 6,1946 INVEN TOR.

Patented Sept. 9, 1947 SAFETY AND LOCKING DEVICE FOR A DISCONNECTINGSWITCH John Gronbeck, Edgewood, R. I.

Application March 6, 1946, Serial No. 652,255

1 Claim. 1

This invention relates to disconnecting switches which are commonly usedin electric power installations for cutting-out selected circuits orparts of circuits for changes or repairs. If such switches are openedunder load, very serious consequences may follow, as they are notdesigned for such operation.

It is the general object of my invention to make it impossible for anoperator to open a disconnecting switch by a single continuous movement,but on the other hand to force him to adopt a step-by-step movementwhich will prevent the formation of a long and dangerous are if thecircuit happens to be under load.

To the attainment of this object, I provide a locking plate mounted on afixed support and operable to engage and lock a switch-bar on initialopening movement thereof. I also provide a spring'acting to move saidlocking plate to inoperative position, together with holding meansnormally overcoming said spring but rendered ineffective by such initialmovement.

My invention further relates to arrangements and combinations of partswhich will be hereinafter described and more particularly pointed out inthe appended claim.

A preferred form of the invention is shown in the drawings, in whichFig. 1 is a side elevation of a disconnecting switch embodying myinvention;

Fig. 2 is a transverse sectional view, taken along the line 2-2 in Fig.1;

Figs. 3 and 4 are views similar to Fig. 2 but showing successiveoperating positions;

Fig. 5 is a partial rear view of the locking plate and associatedsupport, looking in the direction of the arrow 5 in Fig. 1; and

Fig. 6 is a detail sectional View, taken along the line 6--6 in Fig. 2'.

Referring to the drawings, I have shown a disconnecting switch which isin general of an ordinary commercial type and comprises stands orbrackets l and II mounted on insulators l2 and having line wires W and Wsecured thereto.

A switch-bar I is pivoted at IE to the stand or bracket l0, and thestand II is slotted to receive the free or. swinging end of the bar iii.A handle I! is mounted on the bar 15 for yielding outward movement andis provided with a lug l8 normally seated in a notch I!) to hold theswitchbar locked in closed position. The parts thus far described areall of usual construction.

The stand I0 is provided with flanges 20 extending to the right in Fig.1, and a plate or support 22 is mounted in a rearwardly inclined posi- 2tion on the ends of the flanges 20, as also shown in Fig. 1.

A locking plate 30 is pivoted at 3| on the support 22 and is providedwith lower and upper laterally projecting arms 33 and 34.

p The arm 33 has a slight recess 36 (Fig. 6) on its rear face, in whicha spring-pressed ball 31 is normally seated. The ball is mounted in ashort tube 38 and is pressed outward by a spring 39. When the ball 31 isin the recess 36, the plate 30 is held yieldingly in the normal positionshown in Fig. 2 and with the .bar I5 in fully closed position.

The upper arm 34 of the plate 30 has an inverted V-shaped cam notchformed in its under edge and has its outer end cut away or beveled asindicated at 41. A spring (Fig. 5) is mounted at the back of the plate30 and has its upper end hooked behind a stud 5| in said plate. Thelower end is inserted under tension between the rear flange 20 and therear end of the bolt which forms the pivot IS. The spring 50 tends toswing the plate 30 to the left in Fig. 5 or to the right in Figs. 2, 3or 4 but is not strong enough to dislodge the ball 31.

Having described the details of construction of my improved safety andlocking device, the operation thereof is as follows:

The parts are shown in Figs. 1 and 2 with the switch-bar IS in normal orclosed position, and in this position the lower edge of the bar l5engages the upper edge of the arm 33 and holds the same downward in theposition shown in Fig. 2. The spring 39 presses the ball 31 into therecess 36 and thus also holds the plate 30 in the position shown in Fig.2 until the plate is positively moved therefrom.

When the switch is to be opened, initial upward movement of the bar l5causes the top edge of the bar to engage an inclined cam surface 40!;forming part of the V-shaped notch 40, and such engagement will swingthe plate 30 by cam action to the right in Fig. 2 far enough to clearthe recess 36 from the ball 31. The spring 5|] then continues theswinging movement of the plate 3|] until the bar I5 and plate 30 arelocked in the position shown in Fig. 3 by the lug 34a on the end of thearm 34. and with the lower edge of the bar IE only slightly clear of thestand II.

If the circuit controlled by the switch is under load, an arc will thenbe formed but the arc will be of short length and correspondinglyharmless. If an arc is formed, the switch-bar will naturally be returnedimmediately to closed position. If no arc is formed, however, theswitch-bar 15 will be bar engages the upper face of the arm 33 and.

swings the plate 30 to the left until it is returned to its originalposition as shown in Fig. 2.

It will thus appear that I have provided a very simple construction bywhich a step-by-step opening movement of the switch-bar is required andby which a single full-swing openingmovement is positively prevented.The safety of the operator as well as the equipment is thus insured.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claim, but what I claim is:

A safety and locking device for a disconnecting switch having aswitch-bar and a support therefor comprising a locking plate mounted ona fixed pivot on said support and normally operative to engage and locksaid switch-bar in partially open position, yielding means to hold saidplate in normal operative position, cam means engaged by said bar andeffective to cause said locking plate to receive an initial limitedangular shift from normal position to an intermediate position withinlocking range and to simultaneously release said locking plate from saidhold- .ing means, and a spring thereafter effective to move said lockingplate further in the same direction and fully out of the path of saidswitchbar when said switch-bar is given a slight return movement toclear said locking plate.

JOHN W. GRONBECK.

REFERENCES CITED UNITED STATES PATENTS Name Date Strai Oct. 31, 1933Number

